This invention relates to a connector for attaching implements to mobile construction equipment and the like and more particularly to a quick coupler allowing convenient interchangeability of implements on construction equipment.
Heavy equipment is used at construction sites, scrap yards, in roadwork, railroad maintenance, mines, at demolition sites, and elsewhere. Such equipment includes smaller tractors with backhoes, large excavators and other pieces of equipment. Often, excavators and backhoes have a boom attached to the body of the piece of equipment and a stick attached to the end of the boom. An implement such as a digging bucket, an impact hammer, an earth compactor, or another piece of equipment is then attached at the end of the stick. The implement at the end of the stick is often attached by means of a hinge pin connected to the stick and the implement. Additionally, a hydraulic cylinder connected to the stick is also connected to the implement through a link by means of a link pin. This allows the operator of the equipment to position the implement with the boom and stick and also rotate the implement about the end of the stick by means of the stick hydraulic cylinder.
A particular piece of construction equipment may be put to several different uses at the same job site. It may be used with an impact hammer to break-up concrete or rocks. At a different time at the same site, it will be used with a bucket to excavate a trench. Thereafter, the same piece of equipment may be used with a compactor implement when the trench is refilled. In order to efficiently use this versatility, the changing of implements at the end of the stick should be a relatively quick operation. To this end, numerous quick coupler attachments have been provided in the past. Generally, such quick couplers are attached to the stick and stick cylinder link of the piece of equipment. Recesses are provided on the open face of the quick coupler which can engage pins on the implement to be attached. Hydraulic, spring and/or other mechanisms are then used to grasp the pins on the implement.
Such prior art quick couplers sometimes employ hydraulic cylinders to directly drive a closure member around a pin. Other prior art quick couplers use a heavy spring to drive a closure member around a pin. In some instances, the force on the implement in use acts directly against the force of the hydraulic cylinder or spring retaining the implement. Other units require extensive hand manipulation in moving or cocking engagement members. Sometimes such hand manipulations require a good deal of effort as construction equipment is heavy and the quick coupler must therefore be robust. Moreover, the forces applied on construction equipment are often very large also requiring robust connectors, springs or hydraulic cylinders. The construction, demolition, mining, and other environments in which such equipment are used are usually gritty, open to the elements and very hard on equipment.
In accordance with the present invention, there is provided a quick coupler which does not require heavy springs directly biasing a pin grasping member into a closed position or a hydraulic cylinder exerting a large closure force on a pin grasping member.
In accordance with the present invention, there is provided a quick coupler comprising recesses which engage the upper mounting pin on an implement, recesses which engage the lower mounting pin on an implement, a movable latch which is positioned by contact with the pins on the implement only and a gate fixing the latch in the closed position when attached to an implement.
Further in accordance with the invention, the recesses on the quick coupler comprise one set of U-shaped recesses with the opening of the U facing in the direction of the plane defined by the two pins on the implement and the second set of U-shaped recesses with the opening of the U facing perpendicular to the plane defined by the two pins on the implement with the latch engaging the pin in the second set of recesses.
Still further in accordance with the invention, the latch comprises a hook shaped surface with the short leg of the hook forming a closure portion and the long leg of the hook forming an engagement portion and a pin of the implement retained between the closure portion and engagement portion when the latch is in the closed portion.
Still further in accordance with the invention, the latch closure portion engages the lower mounting pin on the implement and the closure portion is shaped so that the lower mounting pin may push by the closure portion when entering the appropriate recess, contact the engagement portion and push the engagement portion until the latch reaches the closed position whereupon the gate can be engaged.
Still further in accordance with the present invention, the latch is rotatable about an axis and has a catch portion with a surface generally extending radially from the latch axis which catch surface engages the gate in the closed position.
Still further in accordance with the present invention, the quick coupler has a frame comprising two side walls with locking apertures coaxial in the side walls and a locking aperture through the latch which is coaxial with the frame locking apertures when the latch is in the closed position. A pin is provided for insertion through the locking apertures and a pin retention structure is provided on the latch fixing the locking pin in place.
Still further in accordance with the invention, a double acting hydraulic cylinder is attached to the gate moving the gate between the open and closed position under operator control.
It is the principal object of the present invention to provide a quick coupler which is robust, reliable, easy to use, and inexpensive to manufacture.
It is another object of the present invention to provide a quick coupler in which a latch is held in the closed position by reason of a robust piece of steel engaging against a second robust piece of steel.
It is yet another object of the present invention to provide a quick coupler in which a control hydraulic cylinder simply moves a gate element into or out of engaged position and does not oppose the force of disengagement.
It is still another object of the present invention to provide a quick coupler using a latch and gate engagement and also a locking pin engagement fixing the attach in the closed, engaged position.
It is yet another object of the present invention to provide a quick coupler which does not require manual cocking of a mechanism into the open position to make it ready for attachment to an implement.
It is still another object of the present invention to provide a quick coupler in which an implement can be engaged, and a gate moved into the closed position from the excavator control station whereupon locking apertures will be aligned with a locking pin easily inserted and fixed in place completing the attachment.
It is yet another object of the present invention to provide a quick coupler which is easily maintained in the field, robust, not prone to failure, and having only a minimum of moving parts.